1. Field of the Invention
The subject invention relates to PCMCIA cards. More particularly, it relates to a modular PCMCIA card comprising a base piece that conforms to the PCMCIA Type I or Type II physical dimensions and an interlocking second part that when added to the first piece conforms to the PCMCIA Type III dimensions.
2. Description of the Prior Art
The PCMCIA (Personal Computer Memory Card International Association) standard was developed for the purpose of providing user installed memory and I/O functions for small form factor digital computer systems. The standard specifies a card containing a printed circuit board. This product is usually referred to as a PC card. There are three PC card formats: Types I, II and III. All three have external dimensions of 54 millimeters by 85.6 millimeters. Thicknesses vary. Type I is 3.3 millimeters thick. Type II is 5 millimeters thick and Type III is 10.5 millimeters thick. The cards look similar to a conventional credit card. The standard specifies a 68 position connector on one end. The 68 position connector plugs into a mating connector mounted on a header which is in turn mounted to a mother board or daughter board which is located inside the host. The header is typically U shaped with the 68 pins at the base of the U. There is a wide variation of headers including headers for different thickness cards; however, the 68 pin connector is common to all PCMCIA cards.
The original PC cards were for memory addition and thus had no interaction with external devices. I/O cards were developed later to add functions such as modems, faxes, network interfaces, multi-media interface, sound cards, etc. In order to handle I/O functions, a second connector is located on the end of the card opposite the 68 pin connector. The I/O connector reaches the outside world through a cable.
Type I and Type II PCMCIA cards fit into the same PCMCIA slots. A Type III card would occupy two vertically stacked PCMCIA Type I/II slots. Most notebook size computers have one or two PCMCIA Type I/II slots. Most subnotebook and handheld computers have but one Type I/II slot. Very few computers of any size have Type III slots yet. However, there is a strong need for the functionality that only the larger volume of a Type III card can provide such as to accommodate a harddisk drive. There is expected to be a strong trend to computers with Type III slots in the coming years, but there is currently a large installed base of computers with Type I/II slots only, and this installed base will grow substantially. Thus there is a need for a modular PCMCIA card that can perform certain functionality as a Type I or II card for those computers that only have a Type I/II slot and at the same time provide Type III card functionality for computers that have a Type III slot.
In addition, as pointed out in the co-pending patent application referenced in the first section of this application, there is a need for a stand alone computer that fits the PCMCIA format. This computer acts as a companion to a desktop or other larger computer. When in the larger computer, the PCMCIA card acts as additional memory. When out of the larger computer, the PCMCIA card is a stand alone computer. Because this is very difficult to accomplish with a Type I or Type II card, it is desirable to have a way to get added volume for the additional components without sacrificing PCMCIA card, Type I or II compatibility.